Open Source software is at the heart of Apple platforms and developer tools, and Apple continues to both lead and make significant contributions to many Open Source projects. Major components of Mac OS X, including the UNIX core, are made available under Apple’s Open Source license, allowing developers and students to view source code, learn from it and submit suggestions and modifications. In addition, Apple uses software created by the Open Source community, such as the HTML rendering engine for Safari, and returns its enhancements to the community.

Apple believes that using Open Source methodology makes Mac OS X a more robust, secure operating system, as its core components have been subjected to the crucible of peer review for decades. Any problems found with this software can be immediately identified and fixed by Apple and the Open Source community.